using System.Collections.Concurrent;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello World!");

app.Run();

void Test()
{
    var dictionary = new ConcurrentDictionary<string, string>();
}

var p = new Person();
if(p is { Name: "aaa" , Length: >0})
{

}
sealed class Person
{
    public int Length { get; set; }
    public string Name { get; set; }
}